const toggle = document.querySelector('#topbar-toggle')
const panel = document.querySelector('#collapsible-panel')
let check = false // 代表没展开
toggle.addEventListener('click',()=>{
    if(check == false){
        toggle.src = 'static/icons/on.svg'
        panel.style.display = 'block'
        check = ! check
    } else {
        toggle.src = 'static/icons/off.svg'
        panel.style.display = 'none'
        check = ! check
    }
})